That's definitely the way I read it too.
I don't go out and buy Pentium 3's and install 256 MB of ram when I read video game requirements. Author must have a very cluttered room.
Visited with a handful of browsers and found no issues (though admittedly, can't log in, not a member), but the system kicks back no errors visiting with an up-to-date Chrome or Firefox.
Worst case, just get an extension that lets you change your browser ID string. Unless it's using some of the proprietary OS hooks (which I can't imagine) it'll never come up.
This is a url to their official website and if you visit the link with JavaScript disabled you'll see what they most likely consider 'officially supported'.
They're not saying you couldn't use anything different/newer though.